JPS60150746A - Absorbing body - Google Patents

Abstract

An absorbent body is provided for absorbing body fluids. The body is generally planar and elongated and is surrounded by a peripheral edge. A portion of the edge is densified so that fluid striking the absorbent body at a point in proximity to the densfied peripheral edge will be transported rapidly away from said point.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to providing a fibrous absorbent material pad for absorbing body fluids, particularly for use in products such as sanitary napkins, panty liners, diapers, etc. This is about a waste absorber.

Generally such products include one or more cores of hydrophilic material such as wood pulp, rayon, tissue, etc. The hydrophilic material (generally of the fibrous type) is provided as a pad having a rectangular or oval shape, and in some instances a shape to better fit the wearer's anatomy. Bad KVi usually has a cover that is permeable to body fluids on the side of the pad that comes into contact with the body, and a cover that is impermeable to that type of liquid on the side of the pad opposite to the side that comes into contact with the body. The purpose of such a body fluid impermeable cover is, of course, to prevent the clothing from becoming soiled or wet.

In general, such products have performed satisfactorily the functions of absorbing and retaining body fluids and protecting the wearer's clothing from dirt and moisture. Normally, when the wearer correctly places and secures the product in the intended position, the body fluid will fall towards or near the center of the product and will be distributed throughout the absorbent medium as the body fluid travels through the wick. Unfortunately, products are often worn incorrectly, either because the wearer is wearing them in the wrong position, or because the wearer is misaligned due to exercise. In such cases, the fluid falls away from the center of the pad, near the peripheral edge. It is believed that this off-centre fall of body fluids is responsible for the very frequent failures associated with the use of these products, i.e., body fluids soiling or wetting the wearer's clothing. .

Therefore, there is a need to create a pad for body fluid absorbent products that protects the user from the untoward consequences of incorrectly positioning the product.

In accordance with the teachings of the present invention, an absorbent body (pad) for a body fluid absorbent product is provided that alleviates the problem of wetting or staining a wearer's clothing due to body fluids falling near the peripheral edges of the pad.

This property is obtained by creating a compressed peripheral edge in a pad-like absorbent body made of fibrous absorbent material. Preferably, such compression line is integral with the majority of the pad,
It should be densely made to have a bulk density at least about 10 times that of the least dense part of the pad. More preferably, the peripheral edge of the pad is at least 20 times as dense as the least dense portion of the pad.

In a preferred embodiment, the pad has a density gradient such that the density gradually increases from the least dense portion of the pad toward the periphery. However, even though it increases gradually, the gradient of increase becomes sharper as it approaches the peripheral edge.
Ultimately, the density of the peripheral edge will be as described above.

Although the advantages of the present invention may actually be realized as long as a portion of the peripheral edge has a density as described above, it is preferred that the compressed peripheral edge surround the entire circumference of the pad.

In a particular embodiment, all or part of the edge of the pad is overlaid with a liquid-impermeable cover to prevent wetting of the user's clothing.

It has been found that, in accordance with the teachings of the present invention, liquid that reaches a point on the peripheral edge of the pad is quickly streaked along the periphery and carried away from that point. This liquid transport is 1n-vit
Observed experimentally in the ro test.

In this test, it was found that products incorporating such pads had very few instances of failure, ie, body fluids being deposited on the outer surface of such products.

The perspective view of FIG. 1 shows a sanitary napkin 10 into which the proposal of the invention has been inserted. 2 and 3 are a cross-sectional view and a longitudinal cross-sectional view of the napkin 10, respectively.

A napkin consists of an absorbent element 12, usually presented in the form of a flat pad. The selection of materials used in the pad of the present invention is not critical. However, it is important that the pad used can be densified by the methods described herein, and that such densification results in the liquid transport properties detailed below.

Preferably, the pad contains loosely bound absorbent hydrophilic materials such as cellulose fibers, such as wood pulp, recycled cellulose or cotton fibers. Such fibers may be chemically or physically modified, and the pad may include such fibers in combination with other natural- as well as synthetic materials such as hydrophilic foams, hydrophilic polymers, etc. I can do it. An excellent material is wood pulp, which is inexpensive, readily available and suitable for the densification specified by the present proposal.

The pad +2I/'i shown in FIGS. 1-3 is wrapped in tissue wrap 14. This is to keep the product together during manufacturing and to help maintain the shape of the final product.

First major surface 15 of napkin 10. Namely, the napkin.
There is a body fluid permeable cover 16 covering the side that is placed against the user's body. Cover 16t! , woven or non-woven materials that are permeable to body fluids that fall onto the surface of the jacket, and such covers are well known to those skilled in the art. In a preferred embodiment, the cover is comprised of a thermoplastic material that can be fused with the other elements of the napkin, such as by heat, pressure, sonic sealing, or the like.

A preferred material for making the cover is a woven fabric consisting of thermally bonded polyester/polyethylene composite fibers. Such composite fibers are fibers consisting of a polyester core surrounded by a polyethylene sheath. Preferably, the composite fibers are made of high density polyethylene, ie at least 0.
94 gm/aa and a density of 1 or more, preferably about 10
More preferably, linear polyethylene having a melt index of about 20 to about 500 is used. Fiber is about 40 to about 60% by weight
, more preferably about 45 to 55 weight parts of polyester, with the remainder being polyethylene. Such fibers may be used in thicknesses of 1 to about 6 denier and lengths of about 1 and
27cm) to about 3-4 inches (7,62N10.16o
o) used in Fabrics made of such fibers,
The fibers are stabilized by heating under near zero pressure to create thermal bonding without destroying the integrity of the fibers.

A body fluid impermeable layer 18 covers the second main surface 17 of the pad 12 (the surface opposite to the surface that contacts the user's body) and at least a portion of the edge 19 of the pad 12. layer 1
8 is there to prevent body fluids from leaking into the underwear, and may be made of any material suitable for this purpose. For example, the layer may be a polymeric film such as polyethylene, polyglopylene, or cellophane, or a normally liquid-permeable material may be treated to become impermeable, such as fluid repellant paper.
) can be used. Conveniently, layer 18 is a heat bondable material, such as polyethylene, which can adhere to layer 16 and completely enclose pad 12.

In the preferred contour layer 20, the nonwoven contour layer forms the outer outer layer of the napkin 10. This non-woven outer layer is intended for aesthetics and its soft feel.

As clearly visible in FIGS. 2 and 3, the outer surface of the napkin 10 has a pressure-sensitive adhesive element 22 attached thereto so that the napkin adheres to the crotch of the wearer's undergarment. As shown in this particular embodiment, these adhesive elements 22 are in the form of three to four longitudinally extending bands, although it will be appreciated by those skilled in the art that the number and shape of these adhesive elements may be varied. It is natural for . Pressure-sensitive adhesives include water-based pressure-sensitive adhesives such as acrylic adhesives (an example of which is vinyl-2-ethyl acetate, which is commonly used in combination with an adhesive such as ethyleneamine). Any of the known compositions suitable for this purpose may be used, including xyl acrylate copolymers). Alternatively, the adhesive may be a fast-setting thermoplastic (hot melt) adhesive, such as block copolymers typified by styrene and butadiene/styrene copolymers. The adhesive element may also include double-sided adhesive tape.

The adhesive part should be carefully sealed before use to prevent any inconvenient adhesion.
It is protected by a release strip 24. The release strip 24 is made of a suitable sheet-like material that is sufficiently adhered to the adhesive element 22 to hold it in place and is easily removed when the napkin 10 is used. A particularly useful material is semi-bleached kraft paper with a silicone coating on the side that contacts the adhesive so that it can be easily removed from the adhesive just before use.

In FIG. 2a, a plot is graphically drawn with the density of the pad 12 shown in FIG. 2 as the vertical axis and the distance f along the line 2-2 as the horizontal axis. As will be seen, the density of the pad increases at a gradual and gradual rate from the point of minimum pad density toward the outer periphery of the pad. In the embodiment shown, the least dense pad portion with respect to the lateral and longitudinal centerlines is the center of the pad. However, it is understood that this example is merely illustrative and that compressive center channels could be provided in the pad, for example, such that the least dense portion of the pad is in a depressed position from the center. Should.

In accordance with the teachings of the present invention, and as clearly shown in Figure 2, the density of the pad increases rapidly as one approaches the periphery of the pad, and at the extremes the density is at least 10 times the density of the lowest density portion, more preferably. At least 20 times. In the example shown in the figure, the peripheral edge density is 1,0 g m/o
c, which is 20 times the density of the pad portion with the lowest density (0.05 gmloo ). The density quoted herein is the local bulk density of the pad, i.e. the weight per unit volume of the pad, including the interstitial space, such as exists between wood valve fibers, in such a unit volume. It will be understood by those skilled in the art that Fi.

FIG. 3a shows a graph plotting the distance along the line 3--3 of the pad 12 shown in FIG. 3, with the vertical axis representing the density and the vertical distance representing the horizontal axis. Again, it can be seen that the density gradually increases from the least dense part of the pad (the center in this example) towards the periphery.

As one approaches the periphery, the density increases rapidly to the values listed here.

In a preferred embodiment, the dense end region is at least 0.1 part distance inward from the extreme extremity, more preferably at least 0.
．． It extends by the distance of two trowels. The density within the peripheral edge region is
It is within the stated values of at least 10 times the density of the densest portion of the pad, more preferably at least 20 times the density of the densest portion of the pad. Although significant benefits can also be obtained by providing the above-mentioned high densities only in the peripheral edge region of the longitudinal center of the pad.

It is even more preferred that the entire peripheral area of the pad be so dense.

The advantages of the present invention are best understood by considering the following examples, which are described in conjunction with the accompanying FIGS. 4-7.

The comparative pad consisted of 8.5 gm of semi-bleached South Pacific pine wood bulb and was made to be 19.6 cm long, 6.6 cm wide, and 1.65 cm thick. Pads representative of prior art pads currently utilized in sanitary napkins on the market have a nearly uniform density of 0.50 gm/ca. The side of the pad is covered with tissue wrap. To simulate the undesirable consequences of liquid falling far from the center, the side of the pad, inward from the longitudinal edge, is 1.2 mm.
Place the liquid on the horizontal center line with a depth of 7 cm. The placed fluid has a surface tension of about 50 dynes/
(In order to resemble JM, this is a menstrual blood substitute containing 1% by weight NaCJ aqueous solution and 0.2% by weight of a surfactant. The surfactant used was manufactured by Φ Chemical Co., Ltd. (Wyande
tte Chemical Corporation o
It is a poly(ethylene oxide)-poly(propylene oxide) block copolymer sold under the trade name Bluronic by F. F. Michigan, USA. The liquid also contains a red pigment.

To place the liquid at the liquid drop point described above, place the tip of the 50 oo billet as close to the pad as possible without actually touching the pad. As soon as the 10aaO liquid is released from the billet, it falls onto the pad (a full billet with a stop clock is used, fully open).

The liquid tends to stay at the point of fall and moves very slowly to adjacent parts of the pad. After almost all of the 10 ca of liquid has fallen, the liquid tends to puddle away from the pad surface. Such conditions cause napkin defects even in perfect napkins; ie, menstrual blood wets the user's underwear. This is true even if the longitudinal ends of the pad are covered with a liquid-impermeable cover as shown in Figures 1-3, i.e., any accumulated liquid will flow over the edge of the impermeable layer and wet the user's underwear. .

FIG. 4 is a photograph of the two pads described above soaked with liquid, showing both the body side and the underwear side.

Line 30 shows the maximum distance that the liquid will travel within 5 minutes after it falls.

Example 1 A pad is made to have the general shape of the pad 12 shown in FIGS. 1 to 3. The pad, made of semi-bleached Southern pine wood pulp, was 19.2 cm long and 5.1 cm wide at the center of the longitudinal section, and had the density gradient shown in Figures 2a and 3a.

Place menstrual blood substitute on the pad as described for the comparative example. FIG. 5 illustrates the liquid transport properties of a first set of such pads, showing both the body and underwear sides of the pad. The pad shown in FIG. 5 is completely surrounded by tissue wrap, as shown in FIGS. 1-3. The pad on the right is identical to the pad of FIGS. 1-3, and the pad on the left includes a compressed central channel 32. Accordingly, along the longitudinal centerline of the pad, the least compressed portion of the pad is the point between the compressed center channel and the compressed peripheral region. Line 34 shows the spread of the liquid immediately after it is deposited. Line 36 shows the spread of the liquid 5 minutes after it has been placed. As can be seen from this photo, unlike prior art pads, liquid is quickly and conveniently carried away from the point of drop. Observations showed that the transport was fast enough to prevent liquid from accumulating at the point of drop.

Example 2 A series of pads are made in the same manner as in Example 1 except that only the body side of the pads is covered with tissue. FIG. 6 shows the spread of liquid placed on this pad, and it can be seen here that the liquid is also rapidly transported.

Example 3 A series of pads are made similar to the pads of Example 1, except that a tissue cover is not used.

FIG. 7 shows the spreading of the liquid placed above it, again showing that rapid transport of the liquid occurs.

Example 4 In order to quantify the results shown in Figures 4 to 7,
As described in Examples 1-3 and Comparative Examples, a number of pads of various shapes described above were impregnated with liquid. The initial spread of liquid along the peripheral edge of the pad was measured immediately after the liquid fell and then again after 5 minutes. The average of these values is shown in Table 1 below for each type of pad.

COMPARATIVE EXAMPLE 9 1.44 2.35 As can be seen from Table 1, the pads of Examples 1-3 incorporating the teachings of the present invention all have a longer initial length compared to the prior art comparative example pads. Indicates longer length, i.e. faster liquid transport.

Example 5 A pad of the series of Example 1 is inserted into a sanitary napkin of the general construction shown in FIGS. 1-3. The napkin was tested using a dynamic testing device (Dynamio Form Testingap).
paratus). In this test, a napkin is hung from a rubber mold shaped like a woman's body. The rubber mold is moved by gears, cams and ronds so that the menstrual blood substitute drips onto the napkin under almost the same conditions as during actual use. The liquid is about 0.2
Drop at a rate of cc/min. And the rubber mold is 60
Cycle/m! Moves at a speed of n. The liquid capacity of the napkin under exercise conditions is measured by the total volume of liquid dripped up to failure, ie, when the underside of the napkin bleeds.

A second series of pads inserted with pads according to the prior art described in the Comparative Examples was similarly tested.

The results of these tests are summarized in Table 2 below.

Comparative example 6 8.53 12.9 50.9 Example 1
6 8.62 11.0 84.4 As can be seen from Table 2, the napkin capacity as measured by this test method increased significantly.

The absorbent bodies of the present invention can be made by several methods known to those skilled in the art. For example, a pad may be created that is thicker at the periphery than at the center and compressed to a uniform thickness to create the density gradient described above. More preferably, a pad of uniform thickness is first made;
It is placed in a mold and compressed to produce a compressed pad in which the peripheral portion is thinner and denser than the central portion, resulting in the aforementioned gradient. The pressure applied to the pads may be uniform, or there may be excess pressure at the extreme edges. Such excess pressure may be applied, for example, by a die-cutter that cuts the pad into the desired shape, or by applying excess pressure that simultaneously creates the mold profile and the pressure gradients described herein.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a sanitary napkin to which an absorbent material according to a first embodiment of the present invention is applied, with a portion cut away to show internal details. FIG. 2 is a cross-sectional view of the sanitary napkin of FIG. 1 taken along line 2--2. Figure 2a graphically illustrates the density gradient across the pad. FIG. 3 is a longitudinal cross-sectional view of the sanitary napkin of FIG. 1 taken along line 3--3. FIG. 3a is a graphical representation of the density gradient in the longitudinal direction of the pad. FIG. 4 is a diagram of a prior art pad exhibiting a disadvantageous liquid distribution condition which the present invention seeks to improve. 5 to 7 are photographs showing the fiber structure of the pad according to the present invention. DESCRIPTION OF SYMBOLS 10... Napkin, 12... Pad, 14... Tissue wrap, 15... Main surface, 16... Cover, 17... Main surface, 18... Body fluid impermeable layer,
19... Edge, 20... Contour layer, 22... Adhesive element. ! Patent applicant: Personal Products Company 21 Procedural Amendment Band (Method) Showa 6%2.2R8 Commissioner of the Japan Patent Office 1, Indication of case: Patent Application No. 186625/1982 2, Title of invention Absorber 3, Make amendments 5, Date of amendment order 6, Subject of amendment (1) Brief explanation column of drawings in the specification (2) Drawing 7, Contents of amendment (1) “Pad” on page 21, line 9 of the specification This is a diagram of
"This is a photograph showing the fiber structure of the pad."
and correct it. (2) Figures 4, 5, 6, and 7 will be corrected as shown in the attached sheet.

Claims (9)

[Claims] (1) An absorbent body made of a fibrous material for absorbing body fluids, said absorbent body being substantially flat and elongated and having a peripheral edge, said peripheral edge being integral with the rest of said absorbent body. A portion of the absorbent body is relatively dense, such that body fluids falling on the body at a point close to the peripheral edge of the absorbent body are quickly carried away from this point by the dense peripheral edge. (2) the density of the dense peripheral edge is at least 10 times the density of the least dense portion of the absorbent body; An absorbent body according to claim 1. 3. The absorbent article of claim 2, wherein the density of the dense peripheral edge is at least 20 times the density of the least dense portion of the absorbent article. (4) the dense peripheral edge extends inwardly from the extreme extremity of the absorbent body a distance of at least 0.1 inch; The absorbent body according to claim 2. 5. The absorbent article of claim 4, wherein the dense peripheral edge extends inwardly from the extreme extremity of the absorbent article a distance of at least 0.2 oIn. (6) The absorbent article according to claim 1, wherein the dense portion of the peripheral edge is at least a peripheral edge of a central portion in the longitudinal direction of the absorbent article. (7) The absorbent body according to claim 1, wherein the dense portion of the peripheral edge extends over substantially the entire peripheral edge of the absorbent body. (8) The absorbent body according to claim 1, wherein the density of the absorbent body increases from the lowest density portion of the absorbent body toward the periphery. (9) The absorbent body according to claim 8, wherein the rate of increase in density is low during the distance from the lowest density portion of the absorbent body to the periphery, and increases as the distance approaches the periphery. Claim 1, wherein the dense area around α1 is at least partially covered by a liquid-impermeable cover.
Absorber described in section. I. The absorbent body according to claim 1, which is inserted into a sanitary napkin. 02 Claim 1 inserted into a disposable diaper
Absorber described in section.